One solution is to go into the dungeons, kill the monsters, and hopefully get some potions after killing the monsters.

Another thing is that at later levels (4+) I've been able to buy them in stores. You might be able to buy them before that, but I don't know for sure.

Yet another alternative is to do an odd job for a guild that sells potions. I've done odd jobs for various guilds, but I haven't actually joined them. They will sometimes make potions available to you. I don't know if any of the patches have fixed any of these things because I haven't played in a while.

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